Under certain load pattern, the geometrically indeterminate pin-jointed mechanisms will present certain shapes to keep static equalization. This paper proposes a matrix-based method to determine the mobility and equil...Under certain load pattern, the geometrically indeterminate pin-jointed mechanisms will present certain shapes to keep static equalization. This paper proposes a matrix-based method to determine the mobility and equilibrium stability of mechanisms according to the effects of the external loads. The first and second variations of the potential energy function of mechanisms under conservative force field are analyzed. Based on the singular value decomposition (SVD) method, a new crite- rion for the mobility and equilibrium stability of mechanisms can be concluded by analyzing the equilibrium matrix. The mobility and stability of mechanisms can be classified by unified matrix formulae. A number of examples are given to demonstrate the proposed criterion. In the end, criteria are summarized in a table.展开更多
Using the rural survey data preserved by the Chinese Academy of Social Sciences＇ （CASS） Institute of Economics, this paper analyzes changes in the level and structure of per capita net income in the eleven villages...Using the rural survey data preserved by the Chinese Academy of Social Sciences＇ （CASS） Institute of Economics, this paper analyzes changes in the level and structure of per capita net income in the eleven villages of Baoding Prefecture, Hebei province, over the 1930-1997periods. According to the surveys, per capita net income level of the villages maintained consistent growth, as indicated by survey data on the years of 1930, 1936, 1957, 1986 and 1997, except for 1946 which saw decline, and enjoyed rapid growth particularly in the years of reform and opening-up after 1986. The changes reflect the national trendsustained decline of the proportion of net income from household operations versus eontinuous growth of the proportion wages income takes of the whole income.展开更多
NMR spectroscopy and X-ray crystallography are two premium methods for determining the atomic structures of macro-biomolecular complexes.Each method has unique strengths and weaknesses.While the two techniques are hig...NMR spectroscopy and X-ray crystallography are two premium methods for determining the atomic structures of macro-biomolecular complexes.Each method has unique strengths and weaknesses.While the two techniques are highly complementary,they have generally been used separately to address the structure and functions of biomolecular complexes.In this review,we emphasize that the combination of NMR spectroscopy and X-ray crystallography offers unique power for elucidating the structures of complicated protein assemblies.We demonstrate,using several recent examples from our own laboratory,that the exquisite sensitivity of NMR spectroscopy in detecting the conformational properties of individual atoms in proteins and their complexes,without any prior knowledge of conformation,is highly valuable for obtaining the high quality crystals necessary for structure determination by X-ray crystallography.Thus NMR spectroscopy,in addition to answering many unique structural biology questions that can be addressed specifically by that technique,can be exceedingly powerful in modern structural biology when combined with other techniques including X-ray crystallography and cryo-electron microscopy.展开更多
Bridges are the most useful part in the transportation network.Any disruption of the bridge structures may hamper the whole transportation system.In the last recent tsunamis,numerous number of bridges were structurall...Bridges are the most useful part in the transportation network.Any disruption of the bridge structures may hamper the whole transportation system.In the last recent tsunamis,numerous number of bridges were structurally damaged by the tsunami waves.Lack of proper provisions of tsunami forces in the design guidelines also contributes to the augmentations of the damage level.Therefore,proper evaluation of the tsunami forces on the bridge girder should be introduced in the design promptly.In this study,laboratory experiments were carried out to reveal the damage mechanism of the bridge girder by assessing the exerted tsunami forces.Both broken and unbroken waves were considered for the analysis.The results showed that measured forces were larger for broken waves than those of unbroken waves.Maximum force of the broken waves was 4.59 times as large as the hydrostatic pressure.Also,waves reached the peak value more rapidly for larger wave heights than those of smaller ones.Additionally,a girder that is placed at a higher position is much vulnerable to tsunami hazard.展开更多
A linear modelling of aeroacoustic waves propagation is discussed. The first point is an existence and uniqueness, theorem. But restrictive assumptions are required on the velocity of the flow. Then a counter example ...A linear modelling of aeroacoustic waves propagation is discussed. The first point is an existence and uniqueness, theorem. But restrictive assumptions are required on the velocity of the flow. Then a counter example proves that they are necessary.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 50378083 and 50638050)the Research Foundation for the Doctoral Program of Higher Education of China (No. 20050335097)
文摘Under certain load pattern, the geometrically indeterminate pin-jointed mechanisms will present certain shapes to keep static equalization. This paper proposes a matrix-based method to determine the mobility and equilibrium stability of mechanisms according to the effects of the external loads. The first and second variations of the potential energy function of mechanisms under conservative force field are analyzed. Based on the singular value decomposition (SVD) method, a new crite- rion for the mobility and equilibrium stability of mechanisms can be concluded by analyzing the equilibrium matrix. The mobility and stability of mechanisms can be classified by unified matrix formulae. A number of examples are given to demonstrate the proposed criterion. In the end, criteria are summarized in a table.
基金For the purposes of this study, the eleven villages of Baoding refer to： Liluohou, Hejiaqiao, Dongguzhuang, Nandeng, Caijiaying, Xuezhuang, Gushang, Xiezhuang, Mengzhuang, Dazhuze, Dayang. However, the data in the 1986 survey only covers six villages. This study was sponsored by National Social Science Foundation （10 CJL008） and the innovation project of CASS＇s Institute of Economics, ＂Rural household economic transition of Wuxi and Baoding during the process of a hundred years of industrialization and urbanization.＂ The authors appreciate support from various scholars.
文摘Using the rural survey data preserved by the Chinese Academy of Social Sciences＇ （CASS） Institute of Economics, this paper analyzes changes in the level and structure of per capita net income in the eleven villages of Baoding Prefecture, Hebei province, over the 1930-1997periods. According to the surveys, per capita net income level of the villages maintained consistent growth, as indicated by survey data on the years of 1930, 1936, 1957, 1986 and 1997, except for 1946 which saw decline, and enjoyed rapid growth particularly in the years of reform and opening-up after 1986. The changes reflect the national trendsustained decline of the proportion of net income from household operations versus eontinuous growth of the proportion wages income takes of the whole income.
基金supported by grants from the Research Grants Council of Hong Kong to M.Z.supported by the National Major Basic Research Program of China (Grant No. 2011CB910500)+3 种基金the National Natural Science Foundation of China (Grant No. 31070657)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KSCX2-YW-R-154)The NMR spectrometers used in our studies were funded by donations from the Hong Kong Jockey Club Charity Foundationthe Special Equipment Grant from RGC of Hong Kong (Grant No. SEG_HKUST06)
文摘NMR spectroscopy and X-ray crystallography are two premium methods for determining the atomic structures of macro-biomolecular complexes.Each method has unique strengths and weaknesses.While the two techniques are highly complementary,they have generally been used separately to address the structure and functions of biomolecular complexes.In this review,we emphasize that the combination of NMR spectroscopy and X-ray crystallography offers unique power for elucidating the structures of complicated protein assemblies.We demonstrate,using several recent examples from our own laboratory,that the exquisite sensitivity of NMR spectroscopy in detecting the conformational properties of individual atoms in proteins and their complexes,without any prior knowledge of conformation,is highly valuable for obtaining the high quality crystals necessary for structure determination by X-ray crystallography.Thus NMR spectroscopy,in addition to answering many unique structural biology questions that can be addressed specifically by that technique,can be exceedingly powerful in modern structural biology when combined with other techniques including X-ray crystallography and cryo-electron microscopy.
基金supported by the University of Malaya and Ministry of Education,PPP fund(Grant No.PG 029-2012B)the High Impact Research Fund(Grant Nos.H-16001-00-D000061,J-16002-00-7383000-000000)
文摘Bridges are the most useful part in the transportation network.Any disruption of the bridge structures may hamper the whole transportation system.In the last recent tsunamis,numerous number of bridges were structurally damaged by the tsunami waves.Lack of proper provisions of tsunami forces in the design guidelines also contributes to the augmentations of the damage level.Therefore,proper evaluation of the tsunami forces on the bridge girder should be introduced in the design promptly.In this study,laboratory experiments were carried out to reveal the damage mechanism of the bridge girder by assessing the exerted tsunami forces.Both broken and unbroken waves were considered for the analysis.The results showed that measured forces were larger for broken waves than those of unbroken waves.Maximum force of the broken waves was 4.59 times as large as the hydrostatic pressure.Also,waves reached the peak value more rapidly for larger wave heights than those of smaller ones.Additionally,a girder that is placed at a higher position is much vulnerable to tsunami hazard.
文摘A linear modelling of aeroacoustic waves propagation is discussed. The first point is an existence and uniqueness, theorem. But restrictive assumptions are required on the velocity of the flow. Then a counter example proves that they are necessary.
